Bipolar disorder is an extremely devastating illness, and increasingly robust evidence indicates that it emerges during adolescence. However, many people with bipolar disorder are not diagnosed until well into their adult lives due to misdiagnosis and failure to seek treatment. Research has found that adolescents who experience mania, the defining characteristic of bipolar disorder, experience significant impairment even if they do not meet full DSM-IV-TR criteria. Consequences of mania in adolescents include academic difficulties, frequent hospitalizations, drug and alcohol abuse, and elevated suicide risk. Also during adolescence, peer relationships become a central mechanism for social maturation and emotional development. In particular, relationships with close friends and romantic partners become integral to adolescents' lives, facilitating identity formation, self-esteem, and emotional maturity. Adolescents' close friendships and romantic relationships also lay the foundation for close relationships in adulthood. The consequences of mania on the development of peer relationships have received little attention. Given the significance of peers in adolescence, it is imperative to understand how adolescents who experience mania function in the peer domain. The proposed study seeks to examine two types of peer relationships, close friendships and romantic relationships, and their association with mania in a community sample of adolescents. In addition, this study will examine two possible mediators of this relationship, social skills and social dominance. Information will be obtained by adolescent self-report in a school setting and also by parent-report questionnaires administered via phone interviews. Mania will be examined dimensionally in light of evidence that full DSM-IV-TR diagnostic criteria are not necessary for mania to cause significant impairment. In addition, due to the overlap between symptoms of mania and symptoms of ADHD, difficulties with attention and hyperactivity will be controlled in the analyses. Data analyses will be conducted using structural equation modeling with Mplus. The proposed study is important from a public health perspective because these findings can potentially contribute to the understanding of bipolar disorder in adolescents and its effects on social and emotional development. Findings will have implications for early identification of bipolar disorder in adolescents, potentially providing a way to differentiate between emerging bipolar disorder and ADHD. Findings will also contribute to more appropriate and effective interventions for adolescents with bipolar disorder by identifying specific aspects of social dysfunction to target during treatment. [unreadable] [unreadable] [unreadable]